By KIMBERLY LOUSHIN
With the equineherpes virus (EHV-1) outbreak that originated at the Women’s Professional Rodeo (WPRA) World Finals and Elite Barrel Race in Waco, Texas, horse owners were naturally concerned about the potential risk to their own horses—regardless of whether they were near Texas or came into contact with horses who’d been in Waco. It’s prompted many to call their veterinarian to request a test for EHV-1.
However, experts Ben Buchanan, DVM, DACVIM, DACVECC, and Katie Flynn, DVMS, cautioned veterinarians at the American Association of Equine Practitioners (AAEP) Convention in Denver, that in the middle of an outbreak they should only be testing horses who are showing clinical signs of EHV-1, not the ones who’d simply been exposed to a horse that tested positive. Flynn and Buchanan emphasized that it was important not to test before clinical signs are present because it could skew outbreak data. This also applies to horses who have not been knowingly exposed to a positive horse.
The reason veterinarians don’t test asymptomatic horses is because horses can be exposed to EHV-1 and become a carrier without showing symptoms. The virus can exist in a latent state for years until stress causes the horse to shed the virus. If an asymptomatic horse tests positive in the middle of an outbreak, it is impossible to know whether the result is due to a latent shed or as part of the outbreak, and accurate reporting of outbreak data is vital.
